“Indoor medicinal cannabis cultivation systems enable year-round cultivation and better control of growing factors, however, such systems are energy and resource intensive. Nutrient deprivation during flowering can trigger nutrient translocation and modulate the production of cannabinoids, which might increase agronomic nutrient use efficiency, and thus, a more sustainable use of fertilizers.” A recent study done by researchers of the University of Hohenheim evaluates the effect of nutrient deprivation during flowering on biomass, CBD yield and nutrient use efficiency of N, P and K. The experiment compares two fertilizer types (mineral and organic) applied in three dilutions (80, 160 and 240 mg N L−1). “This is the first study showing the potential to reduce fertilizer input while maintaining CBD yield of medicinal cannabis,” according to the researchers.
Can fertilizer concentration be reduced?
The study showed that under nutrient stress, inflorescence yield was significantly lower at the final harvest. “The final CBD yield, however, did not show significant differences between 240 and 160 as the lower inflorescence dry matter was at least partly compensated by a higher CBD concentration resulting in 95% of the CBD yield using one-third less fertilizer. It is unclear whether this effect is due to enhanced cannabinoid accumulation due to nutrient stress or simply a dilution effect, indicating a maximum production capacity of cannabinoids,” the researchers say. “Nonetheless, plants experiencing nutrient stress were able to use nutrients more efficiently to produce inflorescence biomass and CBD yield.”
The higher nutrient use efficiency of N, P, and K in nutrient-deprived plants was achieved by a larger mobilization and translocation of nutrients increasing the utilization efficiency of acquired nutrients, the study explains. “The agronomic nutrient use efficiency of CBD yield – for N and K – increased 34% for the organic fertilizers and 72% for the mineral fertilizers comparing the dilution with one-third less nutrients (160) with the highest nutrient concentration (240). Differences in CBD yield between fertilizer types occurred only at the final harvest indicating limitations in nutrient uptake due to nutrient forms in the organic fertilizer. Our results showed a lower acquisition and utilization efficiency for the organic fertilizer, proposing the necessity to improve either the timing of bio-availability of organic fertilizers or the use of soil amendments,” the researchers conclude.
To read the whole study, go to frontiersin.org